Role of Ge in bridging ferromagnetism in the giant magnetocaloric Gd-5(Ge1-xSix)(4) alloys

TitleRole of Ge in bridging ferromagnetism in the giant magnetocaloric Gd-5(Ge1-xSix)(4) alloys
Publication TypeJournal Article
Year of Publication2007
AuthorsHaskel D, Lee YB, Harmon BN, Islam Z, Lang JC, Srajer G, Mudryk Y, Gschneidner KA, Pecharsky VK
Journal TitlePhysical Review Letters
Volume98
Pages247205
Date PublishedJun
Type of ArticleArticle
ISBN Number0031-9007
Accession NumberISI:000247306300047
KeywordsABSORPTION FINE-STRUCTURE, gd-5(si2ge2), gd-5(sixge1-x)(4), MAGNETIC CIRCULAR-DICHROISM, POLARIZED, spectra, systems, transition, X-RAYS
Abstract

X-ray magnetic circular dichroism (XMCD) measurements and density functional theory (DFT) are used to study the electronic conduction states in Gd-5(Ge1-xSix)(4) materials through the first-order bond-breaking magnetostructural transition responsible for their giant magnetocaloric effect. Spin-dependent hybridization between Ge 4p and Gd 5d conduction states, which XMCD senses through the induced magnetic polarization in Ge ions, enables long-range Ruderman-Kittel-Kasuya-Yosida ferromagnetic interactions between Gd 4f moments in adjacent Gd slabs connected by Ge(Si) bonds. These interactions are strong below but weaken above the Ge(Si) bond-breaking transition that destroys 3D ferromagnetic order.

DOI10.1103/PhysRevLett.98.247205
Alternate JournalPhys. Rev. Lett.